1. Field of the Invention
The invention relates to a torque detection device that includes a magnetic flux collecting unit that collects magnetic fluxes from a magnetic yoke and a sensor housing that is formed so as to be integrated with the magnetic flux collecting unit, a method of manufacturing the torque detection device, and an electric power steering system that includes the torque detection device.
2. Discussion of Background
A torque detection device described in US2010/0071481 A1 includes a unit that has magnetic flux collecting rings, a ring holder and a magnetic shield. The magnetic flux collecting rings are fitted to the inner periphery of the ring holder. The magnetic shield is fitted to the outer periphery of the ring holder. The unit is inserted into a housing through an insertion hole formed in the housing, and is fixed to the housing.
In the torque detection device, water may enter the inside of the device through a gap between the unit and the housing. Therefore, in order to improve the waterproof property of the torque detection device, there may be employed a method of manufacturing the torque detection device, according to which the sensor housing is formed so as to be integrated with the unit by supplying resin onto the outer periphery of the unit.
However, with the above-described manufacturing method, the sensor housing and the unit are formed so as to be integrated with each other, and the magnetic shield is located between the ring holder and the sensor housing. Therefore, it is difficult for a worker for an after-process (for example, a quality control person) to check whether the magnetic shield is assembled inside the torque detection device.